Barometer calibration in a location sharing system

ABSTRACT

Methods, systems, and devices for calibrating a barometer of a client device. A server computer accesses historical data including location data, and atmospheric pressure data collected from a plurality of client devices over a period of time. An equation system defined by the historical data is solved. The equation system has a plurality of unknown parameters, the plurality of unknown parameters comprising a barometer bias of a first client device among the plurality of client devices. The first client device is calibrated using the barometer bias.

BACKGROUND

The popularity of electronic messaging, particularly instant messaging, continues to grow. Users increasingly share media content items such as electronic images and videos with each other, reflecting a global demand to communicate more visually. Similarly, users increasingly seek to customize the media content items they share with others, providing challenges to social networking systems seeking to generate custom media content for their members. Embodiments of the present disclosure address these and other issues.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

FIG. 1 is a diagrammatic representation of a networked environment in which the present disclosure may be deployed, in accordance with some example embodiments.

FIG. 2 illustrates a messaging system 200 in accordance with one embodiment.

FIG. 3 is a diagrammatic representation of a data structure as maintained in a database, in accordance with some example embodiments.

FIG. 4 is a diagrammatic representation of a processing environment, in accordance with some example embodiments.

FIG. 5 is a flowchart for an access-limiting process, in accordance with some example embodiments.

FIG. 6 is block diagram showing a software architecture within which the present disclosure may be implemented, in accordance with some example embodiments.

FIG. 7 is a diagrammatic representation of a machine, in the form of a computer system within which a set of instructions may be executed for causing the machine to perform any one or more of the methodologies discussed, in accordance with some example embodiments.

FIG. 8 illustrates a routine in accordance with one embodiment.

FIG. 9 illustrates a routine in accordance with one embodiment.

FIG. 10 illustrates a routine in accordance with one embodiment.

FIG. 11 illustrates a routine in accordance with one embodiment.

FIG. 12 illustrates a user interface in accordance with one embodiment.

FIG. 13 illustrates a user interface in accordance with one embodiment.

DETAILED DESCRIPTION

Embodiments of the present disclosure provide a geographically-based graphical user interface (GUI). This user interface may be referred to herein as a “map GUI,” and may be used in conjunction with a social media application. In some embodiments, the map GUI may include representations of at least approximate respective positions of a user and a user's friends in a social network graph accessed by the social media application using avatars for each respective user.

Various embodiments of the present disclosure provide systems, methods, techniques, instruction sequences, and computing machine program products for calibrating a barometer of a client device within a location sharing system.

As most smartphones contain a barometer, it is possible to collect atmospheric pressure readings from smartphones. Since air pressure decreases with altitude according to a physics formula, it is theoretically possible to determine an altitude of a client device from atmospheric pressure readings. However, at least three other parameters impact the atmospheric pressure readings, namely, weather condition changes, which means atmospheric pressure at sea level changes, barometer bias (each individual barometer has a bias) and local ground level (ground level databases are available, but the data is imprecise). As a consequence, conventional methods for determining a user's altitude are either grossly inaccurate or requires complex hardware installation and calibration.

Motivated by these challenges, some embodiments of the present disclosure provide improvements over conventional methods for accurately determining an altitude of a user. In some embodiments, some of these improvements are achieved by collecting and analyzing location and atmospheric pressure data of a plurality of client devices over a period of time, to determine a barometer bias of the client device of a user.

In some embodiments, the barometer bias of a client device is estimated, and the client device of the user is then calibrated based on the barometer bias. The altitude of the user can then be precisely determined based on atmospheric pressure data acquired by the calibrated client device.

For example, in some embodiments, a server computer accesses historical data including location data, and atmospheric pressure data collected from a plurality of client devices over a period of time. An equation system defined by the historical data is solved. The equation system has a plurality of unknown parameters, the plurality of unknown parameters comprising a barometer bias of each client device of the plurality of client devices. The barometer bias of a first client device is determined, and the at least one client device is calibrated based on the barometer bias.

According to the law of large numbers (LLN), the average of the results obtained from a large number of data acquired should be close to the expected value and will tend to become closer as more data are performed. The LLN guarantees stable long-term results for the averages of the atmospheric pressure data acquired, and as a consequence, for the altitude data estimated. For example, while a single atmospheric pressure reading might be inaccurate due to the barometer bias of the client device, the estimates for the unknown parameters of the equation system will tend towards predictable values.

In some embodiments, a floor level (e.g. the floor number within a building having multiple floors) of the user is determined and shared with the user's approved contact (e.g., friend) accounts via the map GUI. In various embodiments, such data sharing is turned off by default, and the data is only shared if selected for sharing by a privacy setting update provided by the user.

The description that follows includes systems, methods, techniques, instruction sequences, and computing machine program products that embody illustrative embodiments of the disclosure. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide an understanding of various embodiments of the inventive subject matter. It will be evident, however, to those skilled in the art, that embodiments of the inventive subject matter may be practiced without these specific details. In general, well-known instruction instances, protocols, structures, and techniques are not necessarily shown in detail.

FIG. 1 is a block diagram showing an example location sharing system 100 for exchanging location data over a network. The location sharing system 100 includes multiple instances of a client device 102, each of which hosts a number of applications including a location sharing client application 104. Each location sharing client application 104 is communicatively coupled to other instances of the location sharing client application 104 and a location sharing server system 108 via a network 106 (e.g., the Internet).

A location sharing client application 104 is able to communicate and exchange data with another location sharing client application 104 and with the location sharing server system 108 via the network 106. The data exchanged between location sharing client application 104, and between a location sharing client application 104 and the location sharing server system 108, includes functions (e.g., commands to invoke functions) as well as payload data (e.g., location data, text, audio, video or other multimedia data).

The location sharing server system 108 provides server-side functionality via the network 106 to a particular location sharing client application 104. While certain functions of the location sharing system 100 are described herein as being performed by either a location sharing client application 104 or by the location sharing server system 108, the location of certain functionality either within the location sharing client application 104 or the location sharing server system 108 is a design choice. For example, it may be technically preferable to initially deploy certain technology and functionality within the location sharing server system 108, but to later migrate this technology and functionality to the location sharing client application 104 where a client device 102 has a sufficient processing capacity.

The location sharing server system 108 supports various services and operations that are provided to the location sharing client application 104. Such operations include transmitting data to, receiving data from, and processing data generated by the location sharing client application 104. This data may include, geolocation information, message content, client device information, media annotation and overlays, message content persistence conditions, social network information, and live event information, as examples. Data exchanges within the location sharing system 100 are invoked and controlled through functions available via user interfaces (UIs) of the location sharing client application 104.

Turning now specifically to the location sharing server system 108, an Application Program Interface (API) server 110 is coupled to, and provides a programmatic interface to, an application server 112. The application server 112 is communicatively coupled to a database server 118, which facilitates access to a database 120 in which is stored data associated with messages processed by the application server 112.

The Application Program Interface (API) server 110 receives and transmits message data (e.g., commands and message payloads) between the client device 102 and the application server 112. Specifically, the Application Program Interface (API) server 110 provides a set of interfaces (e.g., routines and protocols) that can be called or queried by the location sharing client application 104 in order to invoke functionality of the application server 112. The Application Program Interface (API) server 110 exposes various functions supported by the application server 112, including account registration, login functionality, the sending of messages, via the application server 112, from a particular location sharing client application 104 to another location sharing client application 104, the sending of media files (e.g., images or video) from a location sharing client application 104 to the location sharing server application 114, and for possible access by another location sharing client application 104, the setting of a collection of media data (e.g., story), the retrieval of a list of friends of a user of a client device 102, the retrieval of such collections, the retrieval of messages and content, the adding and deletion of friends to a social graph, the location of friends within a social graph, and opening an application event (e.g., relating to the location sharing client application 104).

The application server 112 hosts a number of applications and subsystems, including a location sharing server application 114, a messaging server application 116 and a social network system 122.

Examples of functions and services supported by the location sharing server application 114 include generating a map GUI. In some embodiments, the map GUI may include representations of at least approximate respective positions of a user and a user's friends in a social network graph accessed by the social media application using avatars for each respective user.

The location sharing server application 114 may receive user authorization to use, or refrain from using, the user's location information. In some embodiments, the location sharing server application 114 may likewise opt to share or not share the user's location with others via the map GUI. In some cases, the user's avatar may be displayed to the user on the display screen of the user's computing device regardless of whether the user is sharing his or her location with other users.

In some embodiments, a user can select groups of other users to which his/her location will be displayed, and may in specify different display attributes for the different respective groups or for different respective individuals. In one example, audience options include: “Best Friends.” “Friends,” and “Custom” (which is an individual-level whitelist of people). In this example, if “Friends” are selected, all new people added to the user's friends list will automatically be able to see their location. If they are already sharing with the user, their avatars will appear on the user's map.

In some embodiments, when viewing the map GUI, the user is able to see the location of all his/her friends that have shared their location with the user on the map, each friend represented by their respective avatar. In some embodiments, if the friend does not have an avatar, the friend may be represented using a profile picture or a default icon displayed at the corresponding location for the friend.

In some embodiments, the user can select between friends on the map via a menu, such as a carousel. In some embodiments, selecting a particular friend automatically centers the map view on the avatar of that friend. Embodiments of the present disclosure may also allow the user to take a variety of actions with the user's friends from within the map GUI. For example, the system may allow the user to chat with the user's friends without leaving the map. In one particular example, the user may select a chat icon from a menu presented in conjunction with the map GUI to initiate a chat session.

The messaging server application 116 implements a number of message processing technologies and functions, particularly related to the aggregation and other processing of content (e.g., textual and multimedia content) included in messages received from multiple instances of the location sharing client application 104. As will be described in further detail, the text and media content from multiple sources may be aggregated into collections of content (e.g., called stories or galleries). These collections are then made available, by the location sharing server application 114, to the location sharing client application 104. Other processor and memory intensive processing of data may also be performed server-side by the location sharing server application 114, in view of the hardware requirements for such processing.

The application server 112 is communicatively coupled to a database server 118, which facilitates access to a database 120 in which is stored data processed by the location sharing server application 114.

The social network system 122 supports various social networking functions services, and makes these functions and services available to the location sharing server application 114. To this end, the social network system 122 maintains and accesses an entity graph 304 (as shown in FIG. 3 ) within the database 120. Examples of functions and services supported by the social network system 122 include the identification of other users of the location sharing system 100 with which a particular user has relationships or is “following”, and also the identification of other entities and interests of a particular user.

FIG. 2 is block diagram illustrating further details regarding the messaging system 200, according to example embodiments. Specifically, the messaging system 200 includes the messaging server application 116 and the messaging client application 124, which in turn embody a number of subsystems, namely an ephemeral timer system 202, a collection management system 204, and an annotation system 206.

The ephemeral timer system 202 is responsible for enforcing the temporary access to content permitted by the messaging client application 124 and the location sharing server application 114. To this end, the ephemeral timer system 202 incorporates a number of timers that, based on duration and display parameters associated with a message, or collection of messages (e.g., a story), selectively display and enable access to messages and associated content via the messaging client application 124. Further details regarding the operation of the ephemeral timer system 202 are provided below.

The collection management system 204 is responsible for managing collections of media (e.g., collections of text, image video and audio data). In some examples, a collection of content (e.g., messages, including images, video, text and audio) may be organized into an “event gallery” or an “event story.” Such a collection may be made available for a specified time period, such as the duration of an event to which the content relates. For example, content relating to a music concert may be made available as a “story” for the duration of that music concert. The collection management system 204 may also be responsible for publishing an icon that provides notification of the existence of a particular collection to the user interface of the messaging client application 124.

The collection management system 204 furthermore includes a curation interface 208 that allows a collection manager to manage and curate a particular collection of content. For example, the curation interface 208 enables an event organizer to curate a collection of content relating to a specific event (e.g., delete inappropriate content or redundant messages). Additionally, the collection management system 204 employs machine vision (or image recognition technology) and content rules to automatically curate a content collection. In certain embodiments, compensation may be paid to a user for inclusion of user-generated content into a collection. In such cases, the curation interface 208 operates to automatically make payments to such users for the use of their content.

The annotation system 206 provides various functions that enable a user to annotate or otherwise modify or edit media content associated with a message. For example, the annotation system 206 provides functions related to the generation and publishing of media overlays for messages processed by the location sharing system 100. The annotation system 206 operatively supplies a media overlay or supplementation (e.g., an image filter) to the messaging client application 124 based on a geolocation of the client device 102. In another example, the annotation system 206 operatively supplies a media overlay to the messaging client application 124 based on other information, such as social network information of the user of the client device 102. A media overlay may include audio and visual content and visual effects. Examples of audio and visual content include pictures, texts, logos, animations, and sound effects. An example of a visual effect includes color overlaying. The audio and visual content or the visual effects can be applied to a media content item (e.g., a photo) at the client device 102. For example, the media overlay may include text that can be overlaid on top of a photograph taken by the client device 102. In another example, the media overlay includes an identification of a location overlay (e.g., Venice beach), a name of a live event, or a name of a merchant overlay (e.g., Beach Coffee House). In another example, the annotation system 206 uses the geolocation of the client device 102 to identify a media overlay that includes the name of a merchant at the geolocation of the client device 102. The media overlay may include other indicia associated with the merchant. The media overlays may be stored in the database 120 and accessed through the database server 118.

In one example embodiment, the annotation system 206 provides a user-based publication platform that enables users to select a geolocation on a map and upload content associated with the selected geolocation. The user may also specify circumstances under which a particular media overlay should be offered to other users. The annotation system 206 generates a media overlay that includes the uploaded content and associates the uploaded content with the selected geolocation.

In another example embodiment, the annotation system 206 provides a merchant-based publication platform that enables merchants to select a particular media overlay associated with a geolocation via a bidding process. For example, the annotation system 206 associates the media overlay of a highest bidding merchant with a corresponding geolocation for a predefined amount of time.

FIG. 3 is a schematic diagram illustrating data structures 300 which may be stored in the database 120 of the location sharing server system 108, according to certain example embodiments. While the content of the database 120 is shown to comprise a number of tables, it will be appreciated that the data could be stored in other types of data structures (e.g., as an object-oriented database).

The database 120 includes message data stored within a message table 314. An entity table 302 stores entity data, including an entity graph 304. Entities for which records are maintained within the entity table 302 may include individuals (e.g., users), corporate entities, organizations, objects, places, events, etc. Regardless of type, any entity regarding which the location sharing server system 108 stores data may be a recognized entity. Each entity is provided with a unique identifier, as well as an entity type identifier (not shown). The entity graph 304 furthermore stores information regarding relationships and associations between entities. Such relationships may be social, professional (e.g., work at a common corporation or organization) interested-based or activity-based, merely for example. A location table 306 stores historical and current activity data of users (e.g., geolocation information determined by a GPS unit of client devices (e.g., client device 102). An atmospheric pressure table 308 stores historical and current activity data of users (e.g., geolocation information determined by a GPS unit of client devices (e.g., client device 102). A barometer bias table 310 stores barometer bias determined for a plurality of client devices (e.g., client device 102). A ground level table 312 stores a ground level dataset storing local ground levels for a plurality of geographical locations (e.g., geographical coordinates) for a plurality of geographical locations, and optionally, a ground level map.

Turning now to FIG. 4 , there is shown a diagrammatic representation of a processing environment 400, which includes at least a processor 402 (e.g., a GPU, CPU or combination thereof).

The processor 402 is shown to be coupled to a power source 404, and to include (either permanently configured or temporarily instantiated) modules, namely a location component 408, a calibration component 418, and a map GUI component 416. The location component 408 generates historical location data of a user by consolidating location data collected over time from one or more client device (e.g., client device 102) associated with the user. The pressure component 410 generates historical atmospheric pressure data of a user by consolidating atmospheric pressure data collected over time from one or more client device (e.g., client device 102) associated with the user. The calibration component 418 accesses atmospheric pressure data from client devices (e.g., client device 102), retrieves a barometer bias of the client device from the barometer bias table 310, and determines a calibrated atmospheric pressure from the atmospheric pressure data by correcting the barometer bias of the client device. The altitude component 412 generates accesses atmospheric pressure data from client devices (e.g., client device 102) and determines an altitude (e.g., height above sea level of a location) of the client device based on the atmospheric pressure data. The ground level component 414 accesses location data and altitude data of users and determines a local ground level (e.g., height of the ground above sea level at a particular location). The ground level component 414 may also generate a ground level map based on the ground level data. The map GUI component 416 operationally generates user interfaces and causes the user interfaces to be displayed on client devices. As illustrated, the processor 402 may be communicatively coupled to another processor 406.

FIG. 5 is a schematic diagram illustrating an access-limiting process 500, in terms of which access to content (e.g., an ephemeral message 502, and associated multimedia payload of data) or a content collection (e.g., an ephemeral message group 506) may be time-limited (e.g., made ephemeral).

An ephemeral message 502 is shown to be associated with a message duration parameter 508, the value of which determines an amount of time that the ephemeral message 502 will be displayed to a receiving user of the ephemeral message 502 by the location sharing client application 104. In one embodiment, an ephemeral message 502 is viewable by a receiving user for up to a maximum of 10 seconds, depending on the amount of time that the sending user specifies using the message duration parameter 508.

The message duration parameter 508 and the message receiver identifier 518 are shown to be inputs to a message timer 514, which is responsible for determining the amount of time that the ephemeral message 502 is shown to a particular receiving user identified by the message receiver identifier 518. In particular, the ephemeral message 502 will only be shown to the relevant receiving user for a time period determined by the value of the message duration parameter 508. The message timer 514 is shown to provide output to a more generalized ephemeral timer system 504, which is responsible for the overall timing of display of content (e.g., an ephemeral message 502) to a receiving user.

The ephemeral message 502 is shown in FIG. 5 to be included within an ephemeral message group 506 (e.g., a collection of messages in a personal story, or an event story). The ephemeral message group 506 has an associated group duration parameter 510, a value of which determines a time-duration for which the ephemeral message group 506 is presented and accessible to users of the location sharing system 100. The group duration parameter 510, for example, may be the duration of a music concert, where the ephemeral message group 506 is a collection of content pertaining to that concert. Alternatively, a user (either the owning user or a curator user) may specify the value for the group duration parameter 510 when performing the setup and creation of the ephemeral message group 506.

Additionally, each ephemeral message 502 within the ephemeral message group 506 has an associated group participation parameter 512, a value of which determines the duration of time for which the ephemeral message 502 will be accessible within the context of the ephemeral message group 506. Accordingly, a particular ephemeral message group 506 may “expire” and become inaccessible within the context of the ephemeral message group 506, prior to the ephemeral message group 506 itself expiring in terms of the group duration parameter 510. The group duration parameter 510, group participation parameter 512, and message receiver identifier 518 each provide input to a group timer 516, which operationally determines, firstly, whether a particular ephemeral message 502 of the ephemeral message group 506 will be displayed to a particular receiving user and, if so, for how long. Note that the ephemeral message group 506 is also aware of the identity of the particular receiving user as a result of the message receiver identifier 518.

Accordingly, the group timer 516 operationally controls the overall lifespan of an associated ephemeral message group 506, as well as an individual ephemeral message 502 included in the ephemeral message group 506. In one embodiment, each and every ephemeral message 502 within the ephemeral message group 506 remains viewable and accessible for a time-period specified by the group duration parameter 510. In a further embodiment, a certain ephemeral message 502 may expire, within the context of ephemeral message group 506, based on a group participation parameter 512. Note that a message duration parameter 508 may still determine the duration of time for which a particular ephemeral message 502 is displayed to a receiving user, even within the context of the ephemeral message group 506. Accordingly, the message duration parameter 508 determines the duration of time that a particular ephemeral message 502 is displayed to a receiving user, regardless of whether the receiving user is viewing that ephemeral message 502 inside or outside the context of an ephemeral message group 506.

The ephemeral timer system 504 may furthermore operationally remove a particular ephemeral message 502 from the ephemeral message group 506 based on a determination that it has exceeded an associated group participation parameter 512. For example, when a sending user has established a group participation parameter 512 of 24 hours from posting, the ephemeral timer system 504 will remove the relevant ephemeral message 502 from the ephemeral message group 506 after the specified 24 hours. The ephemeral timer system 504 also operates to remove an ephemeral message group 506 either when the group participation parameter 512 for each and every ephemeral message 502 within the ephemeral message group 506 has expired, or when the ephemeral message group 506 itself has expired in terms of the group duration parameter 510.

In certain use cases, a creator of a particular ephemeral message group 506 may specify an indefinite group duration parameter 510. In this case, the expiration of the group participation parameter 512 for the last remaining ephemeral message 502 within the ephemeral message group 506 will determine when the ephemeral message group 506 itself expires. In this case, a new ephemeral message 502, added to the ephemeral message group 506, with a new group participation parameter 512, effectively extends the life of an ephemeral message group 506 to equal the value of the group participation parameter 512.

Responsive to the ephemeral timer system 504 determining that an ephemeral message group 506 has expired (e.g., is no longer accessible), the ephemeral timer system 504 communicates with the location sharing system 100 (and, for example, specifically the location sharing client application 104) to cause an indicium (e.g., an icon) associated with the relevant ephemeral message group 506 to no longer be displayed within a user interface of the location sharing client application 104. Similarly, when the ephemeral timer system 202 determines that the message duration parameter 508 for a particular ephemeral message 502 has expired, the ephemeral timer system 504 causes the location sharing client application 104 to no longer display an indicium (e.g., an icon or textual identification) associated with the ephemeral message 502.

FIG. 6 is a block diagram 600 illustrating a software architecture 604, which can be installed on any one or more of the devices described herein. The software architecture 604 is supported by hardware such as a machine 602 that includes processors 620, memory 626, and I/O components 638. In this example, the software architecture 604 can be conceptualized as a stack of layers, where each layer provides a particular functionality. The software architecture 604 includes layers such as an operating system 612, libraries 610, frameworks 608, and applications 606. Operationally, the applications 606 invoke API calls 650 through the software stack and receive messages 652 in response to the API calls 650.

The operating system 612 manages hardware resources and provides common services. The operating system 612 includes, for example, a kernel 614, services 616, and drivers 622. The kernel 614 acts as an abstraction layer between the hardware and the other software layers. For example, the kernel 614 provides memory management, processor management (e.g., scheduling), component management, networking, and security settings, among other functionality. The services 616 can provide other common services for the other software layers. The drivers 622 are responsible for controlling or interfacing with the underlying hardware. For instance, the drivers 622 can include display drivers, camera drivers, BLUETOOTH® or BLUETOOTH® Low Energy drivers, flash memory drivers, serial communication drivers (e.g., Universal Serial Bus (USB) drivers), WI-FI® drivers, audio drivers, power management drivers, and so forth.

The libraries 610 provide a low-level common infrastructure used by the applications 606. The libraries 610 can include system libraries 618 (e.g., C standard library) that provide functions such as memory allocation functions, string manipulation functions, mathematic functions, and the like. In addition, the libraries 610 can include API libraries 624 such as media libraries (e.g., libraries to support presentation and manipulation of various media formats such as Moving Picture Experts Group-4 (MPEG4), Advanced Video Coding (H.264 or AVC), Moving Picture Experts Group Layer-3 (MP3), Advanced Audio Coding (AAC), Adaptive Multi-Rate (AMR) audio codec, Joint Photographic Experts Group (JPEG or JPG), or Portable Network Graphics (PNG)), graphics libraries (e.g., an OpenGL framework used to render in two dimensions (2D) and three dimensions (3D) in a graphic content on a display), database libraries (e.g., SQLite to provide various relational database functions), web libraries (e.g., WebKit to provide web browsing functionality), and the like. The libraries 610 can also include a wide variety of other libraries 628 to provide many other APIs to the applications 606.

The frameworks 608 provide a high-level common infrastructure that is used by the applications 606. For example, the frameworks 608 provide various graphical user interface (GUI) functions, high-level resource management, and high-level location services. The frameworks 608 can provide a broad spectrum of other APIs that can be used by the applications 606, some of which may be specific to a particular operating system or platform.

In an example embodiment, the applications 606 may include a home application 636, a contacts application 630, a browser application 632, a book reader application 634, a location application 642, a media application 644, a messaging application 646, a game application 648, and a broad assortment of other applications such as third-party applications 640. The applications 606 are programs that execute functions defined in the programs. Various programming languages can be employed to create one or more of the applications 606, structured in a variety of manners, such as object-oriented programming languages (e.g., Objective-C, Java, or C++) or procedural programming languages (e.g., C or assembly language). In a specific example, the third-party applications 640 (e.g., applications developed using the ANDROID™ or IOS™ software development kit (SDK) by an entity other than the vendor of the particular platform) may be mobile software running on a mobile operating system such as IOS™, ANDROID™, WINDOWS® Phone, or another mobile operating system. In this example, the third-party applications 640 can invoke the API calls 650 provided by the operating system 612 to facilitate functionality described herein.

FIG. 7 is a diagrammatic representation of a machine 700 within which instructions 708 (e.g., software, a program, an application, an applet, an app, or other executable code) for causing the machine 700 to perform any one or more of the methodologies discussed herein may be executed. For example, the instructions 708 may cause the machine 700 to execute any one or more of the methods described herein. The instructions 708 transform the general, non-programmed machine 700 into a particular machine 700 programmed to carry out the described and illustrated functions in the manner described. The machine 700 may operate as a standalone device or may be coupled (e.g., networked) to other machines. In a networked deployment, the machine 700 may operate in the capacity of a server machine or a client machine in a server-client network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The machine 700 may comprise, but not be limited to, a server computer, a client computer, a personal computer (PC), a tablet computer, a laptop computer, a netbook, a set-top box (STB), a PDA, an entertainment media system, a cellular telephone, a smart phone, a mobile device, a wearable device (e.g., a smart watch), a smart home device (e.g., a smart appliance), other smart devices, a web appliance, a network router, a network switch, a network bridge, or any machine capable of executing the instructions 708, sequentially or otherwise, that specify actions to be taken by the machine 700. Further, while only a single machine 700 is illustrated, the term “machine” shall also be taken to include a collection of machines that individually or jointly execute the instructions 708 to perform any one or more of the methodologies discussed herein.

The machine 700 may include processors 702, memory 704, and I/O components 744, which may be configured to communicate with each other via a bus 746. In an example embodiment, the processors 702 (e.g., a Central Processing Unit (CPU), a Reduced Instruction Set Computing (RISC) processor, a Complex Instruction Set Computing (CISC) processor, a Graphics Processing Unit (GPU), a Digital Signal Processor (DSP), an ASIC, a Radio-Frequency Integrated Circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, a processor 706 and a processor 710 that execute the instructions 708. The term “processor” is intended to include multi-core processors that may comprise two or more independent processors (sometimes referred to as “cores”) that may execute instructions contemporaneously. Although FIG. 7 shows multiple processors 702, the machine 700 may include a single processor with a single core, a single processor with multiple cores (e.g., a multi-core processor), multiple processors with a single core, multiple processors with multiples cores, or any combination thereof.

The memory 704 includes a main memory 712, a static memory 714, and a storage unit 716, both accessible to the processors 702 via the bus 746. The main memory 704, the static memory 714, and storage unit 716 store the instructions 708 embodying any one or more of the methodologies or functions described herein. The instructions 708 may also reside, completely or partially, within the main memory 712, within the static memory 714, within machine-readable medium 718 within the storage unit 716, within at least one of the processors 702 (e.g., within the processor's cache memory), or any suitable combination thereof, during execution thereof by the machine 700.

The I/O components 744 may include a wide variety of components to receive input, provide output, produce output, transmit information, exchange information, capture measurements, and so on. The specific I/O components 744 that are included in a particular machine will depend on the type of machine. For example, portable machines such as mobile phones may include a touch input device or other such input mechanisms, while a headless server machine will likely not include such a touch input device. It will be appreciated that the I/O components 744 may include many other components that are not shown in FIG. 7 . In various example embodiments, the I/O components 744 may include output components 728 and input components 730. The output components 728 may include visual components (e.g., a display such as a plasma display panel (PDP), a light emitting diode (LED) display, a liquid crystal display (LCD), a projector, or a cathode ray tube (CRT)), acoustic components (e.g., speakers), haptic components (e.g., a vibratory motor, resistance mechanisms), other signal generators, and so forth. The input components 730 may include alphanumeric input components (e.g., a keyboard, a touch screen configured to receive alphanumeric input, a photo-optical keyboard, or other alphanumeric input components), point-based input components (e.g., a mouse, a touchpad, a trackball, a joystick, a motion sensor, or another pointing instrument), tactile input components (e.g., a physical button, a touch screen that provides location and/or force of touches or touch gestures, or other tactile input components), audio input components (e.g., a microphone), and the like.

In embodiments, the I/O components 744 include a pressure component 736 (e.g., a barometer). In further example embodiments, the I/O components 744 may further include biometric components 732, motion components 734, environmental components 738, or position components 740, among a wide array of other components. For example, the biometric components 732 include components to detect expressions (e.g., hand expressions, facial expressions, vocal expressions, body gestures, or eye tracking), measure bio-signals (e.g., blood pressure, heart rate, body temperature, perspiration, or brain waves), identify a person (e.g., voice identification, retinal identification, facial identification, fingerprint identification, or electroencephalogram-based identification), and the like. The motion components 734 include acceleration sensor components (e.g., accelerometer), gravitation sensor components, rotation sensor components (e.g., gyroscope), and so forth. The environmental components 738 include, for example, illumination sensor components (e.g., photometer), temperature sensor components (e.g., one or more thermometers that detect ambient temperature), humidity sensor components, acoustic sensor components (e.g., one or more microphones that detect background noise), proximity sensor components (e.g., infrared sensors that detect nearby objects), gas sensors (e.g., gas detection sensors to detection concentrations of hazardous gases for safety or to measure pollutants in the atmosphere), or other components that may provide indications, measurements, or signals corresponding to a surrounding physical environment. The position components 740 include location sensor components (e.g., a GPS receiver component), altitude sensor components (e.g., altimeters or barometers that detect air pressure from which altitude may be derived), orientation sensor components (e.g., magnetometers), and the like.

Communication may be implemented using a wide variety of technologies. The I/O components 744 further include communication components 742 operable to couple the machine 700 to a network 720 or devices 722 via a coupling 724 and a coupling 726, respectively. For example, the communication components 742 may include a network interface component or another suitable device to interface with the network 720. In further examples, the communication components 742 may include wired communication components, wireless communication components, cellular communication components, Near Field Communication (NFC) components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components to provide communication via other modalities. The devices 722 may be another machine or any of a wide variety of peripheral devices (e.g., a peripheral device coupled via a USB).

Moreover, the communication components 742 may detect identifiers or include components operable to detect identifiers. For example, the communication components 742 may include Radio Frequency Identification (RFID) tag reader components, NFC smart tag detection components, optical reader components (e.g., an optical sensor to detect one-dimensional bar codes such as Universal Product Code (UPC) bar code, multi-dimensional bar codes such as Quick Response (QR) code, Aztec code, Data Matrix, Dataglyph, MaxiCode, PDF417, Ultra Code, UCC RSS-2D bar code, and other optical codes), or acoustic detection components (e.g., microphones to identify tagged audio signals). In addition, a variety of information may be derived via the communication components 742, such as location via Internet Protocol (IP) geolocation, location via Wi-Fi® signal triangulation, location via detecting an NFC beacon signal that may indicate a particular location, and so forth.

The various memories (e.g., memory 704, main memory 712, static memory 714, and/or memory of the processors 702) and/or storage unit 716 may store one or more sets of instructions and data structures (e.g., software) embodying or used by any one or more of the methodologies or functions described herein. These instructions (e.g., the instructions 708), when executed by processors 702, cause various operations to implement the disclosed embodiments.

The instructions 708 may be transmitted or received over the network 720, using a transmission medium, via a network interface device (e.g., a network interface component included in the communication components 742) and using any one of a number of well-known transfer protocols (e.g., hypertext transfer protocol (HTTP)). Similarly, the instructions 708 may be transmitted or received using a transmission medium via the coupling 726 (e.g., a peer-to-peer coupling) to the devices 722.

FIG. 8 is a flowchart illustrating a method 800 for calibrating a barometer of a client device. The method 800 may be embodied in computer-readable instructions for execution by one or more processors (e.g., processor 402) such that the steps of the method 800 may be performed in part or in whole by functional components (e.g., location component 408, pressure component 410, calibration component 418) of a processing environment 400 of a system (e.g., application server 112); accordingly, the method 800 is described below by way of example with reference thereto. However, it shall be appreciated that the method 800 may be deployed on various other hardware configurations and is not intended to be limited to the functional components of the processing environment 400.

In block 802, method 800 accesses, from a database (e.g., database 120) coupled to a server computer (e.g., application server 112), historical data of a plurality of users. The historical data includes location data and atmospheric pressure data. The location data may be generated by one or more location sensors (e.g., position components 740) coupled to the client device. In some embodiments, the location sensors may include a global positioning sensor (GPS) component integrated in the client device, as well as other types of location sensors. The atmospheric pressure data may be generated by one or more pressure sensors coupled to the client device. In some embodiments, the pressure sensors may include a barometer component integrated in the client device, as well as other types of pressure sensors. The historical data of a user may be generated by consolidating data collected over a period of time (e.g., a year) from one or more client devices (e.g., client device 102) associated with the user. The historical data may include a plurality of data points, each data point being defined by at least a set of geographical coordinates, an atmospheric pressure reading, and a time stamp. A data point may be extracted by consolidating the data received from a client device (e.g., client device 102) over a period of time during which the location of the client device stayed within a maximum range for a minimum amount of time.

The system may need to receive authorization from the user to utilize data from the user's client devices prior to performing the remaining steps of method 800. Such authorization may be obtained via acceptance of a terms of service for utilizing an online social network or other service provided by the system, by acceptance on a case-by-case basis by the first user (e.g., via popups displayed on the user's computing device) or using any other suitable method for obtaining authorization by the user(s).

In block 804, method 800 solves an equation system, using one or more processors of the server computer, the equation system being defined by the historical data. The equation system has a plurality of parameters. The equation system may be a parametric model (e.g., a family of distributions that can be described using a finite number of parameters). Some of these parameters are unknown parameters. The plurality of parameters comprises a barometer bias of one or more client devices of the plurality of client devices, including a first client device. The barometer bias may include one or more parameters (e.g., an offset parameter and a slope parameter). The plurality of parameters may further comprise, for each data point, a location (e.g., geographical coordinates), an atmospheric pressure, an altitude (e.g., height above sea level of the location), a ground level (e.g., height of the ground above sea level at the particular location), and an atmospheric pressure at sea level. Information about the ground level may be retrieve from a ground level database. Information about the atmospheric pressure at sea level may be accessed from a weather service server. In addition, the parameters are tied by one or more of the following relations.

-   -   the barometer bias of a client device is constant;     -   the atmospheric pressure readings acquired by two client devices         located in the proximity of each other (e.g., within a preset         distance, like, for example, 1 meter) should be identical;     -   atmospheric pressure is linked with altitude according to the         barometric formula, sometimes called the exponential atmosphere         or isothermal atmosphere. The barometric formula models how the         atmospheric pressure changes with altitude. The atmospheric         pressure drops approximately by 11.3 Pa (pascal) per meter in         first 1000 meters above sea level.         The equation system may further be solved based on a set of data         points for which all the parameters are known. The value of each         parameter of these points may be retrieved from a database, or         measured with appropriate equipment.

According to the LLN, the average of the results obtained from the atmospheric pressure data collected should be close to the exact value and will tend to become closer as more atmospheric pressure data are acquired. As a consequence, the estimates for the barometer bias of the first client device will tend towards an exact value.

In block 806, method 800 calibrates the first client device based on the barometer bias of the first client device determined at block 806. The system may store the barometer bias determined for the client device in a table (e.g., barometer bias table 310) stored in a database (e.g., database 120) coupled to a server computer (e.g., application server 112).

Once the client device is calibrated, an accurate atmospheric pressure value may be determined from the atmospheric pressure data acquired by the client device. The location sharing system may use the atmospheric pressure data acquired by the client device to determine various information.

In embodiments, the location sharing system may determine that the user is moving based on detecting an atmospheric pressure drop (e.g., Bernoulli law). The location sharing system may also determine that the user did not move based on the atmospheric pressure acquired by the client device being constant.

In embodiments, once the client device is calibrated, an accurate altitude of the client device may be determined from the atmospheric pressure data acquired by the client device. The location sharing system may use the altitude of a client device to determine various information, such as a floor level on which the user is located.

As shown in FIG. 9 the method 800 may further include a block 902, a block 904, a block 906, a block 908, a block 910, and a block 912, according to some embodiments. Consistent with some embodiments, block 902, block 904, block 906, block 908, block 910, and block 912 may be performed after (e.g., as sub-blocks or as a subroutine) of block 806, where the system calibrates the first client device associated with a first user.

In block 902, method 800 receives, from the first client device, an electronic communication containing location data and atmospheric pressure data acquired by the first client device.

In block 904, method 800 determines a current location of the first client device, based on the location data.

In block 906, method 800 determines a current altitude of the first client device, based on the atmospheric pressure data. The current altitude may be determined as a height above sea level of the first client device. The current altitude may be determined using the barometric formula.

In block 908, method 800 retrieves, from a ground level dataset (e.g., ground level table 312), a local ground level corresponding to the current location of the user.

In block 910, method 800 determines a floor level on which the first user is located, based on the local ground level and the current altitude of the first client device. A height of the first client device above ground level is computed by subtracting the local ground level from the current altitude of the first client device.

The floor level may be estimated by computing how many floor levels are included in the height of the first client device above ground level. The floor level may be estimated based on an average height of a level (e.g., 10 feet (3 m)). If available, data specific to the building in which the first user is located, including a number of floors and a height of each level may be accessed from a database, and the floor level may be estimated based on the building specific data.

A number of floor levels and their respective altitude above ground may also be determined by clustering historical data corresponding to the location of a building based on altitude similarity. The data points may be extracted from the historical data, the altitude of each data point being determined from the historical pressure data after compensating for the barometer bias of the client device. The data points may also be acquired by calibrated client devices, the altitude of each data point being determined from the atmospheric pressure data acquired by the calibrated client device. A data point may be extracted by consolidating the data received from a client device (e.g., client device 102) over a period of time during which the altitude of the client device stayed within a maximum altitude range. Data that is not stable vertically is filtered out, since it is likely to correspond to a user taking the stairs or the elevator. Each cluster is identified as a floor of the building. An altitude of each floor is determined based on the altitude of the data points of the cluster (e.g., an average of the altitude of the data points of the cluster).

In block 912, based on determining that a floor level on which the first user is located, the system (e.g., location sharing server application 114) initiates transmission of data to a second client device (e.g., client device 102) of the second user, the data comprising the floor level on which the first user is located, for display, on a display screen of the second client device. The system may cause display, on a display screen of the second client device, of a user interface (e.g., user interface 1200 of FIG. 12 ) including a map depicting an icon indicating the floor level on which the first user is located alongside the avatar of the first user.

As shown in FIG. 10 the method 800 may further include a block 1002, a block 1004, a block 1006, a block 1008, a block 1010 and a block 1012, according to some embodiments. Consistent with some embodiments, block 1002, block 1004, block 1006, block 1008, block 1010 and block 1012 may be performed after (e.g., as sub-blocks or as a subroutine) of block 806, where the system calibrates the client device.

In block 1002, method 800 receives, from the client device, an electronic communication containing atmospheric pressure data, and location data.

In block 1004, method 800 determines that the user is at ground level, based on the location data. In embodiments, the system determines a speed of the user based on the location data. The system then determines that the user is at ground level based on determining that the speed of the user is above a speed threshold over a distance longer than a distance threshold. Indeed, a speed of the user being above a speed threshold, combined with an itinerary of the user that is longer than a distance threshold is characteristic of the user being on the ground (e.g., walking down a street).

In block 1006, method 800 determines a current altitude of the client device, based on the atmospheric pressure data. In particular, the altitude of the user may be determined from the atmospheric pressure data using the barometric formula.

In block 1008, method 800 determines a ground level, based on the altitude of the client device. Since the user is at ground level, the current altitude of the client device is approximately equal to the ground level at the current location of the client device. In embodiments, the ground level is computed as the current altitude of the client device minus a preset distance (e.g., 1 meter).

In block 1010, method 800 adds the ground level computed at block 1010, associated with the current location of the client device, to a ground level dataset (e.g., ground level table 312).

In block 1012, method 800 may build a ground level map based on the ground level dataset.

As shown in FIG. 11 , the method 800 may further include a block 1104, a block 1106, a block 1108, and a block 1110, according to some embodiments. Consistent with some embodiments, block 1104, block 1106, block 1108, and block 1110 may be performed after (e.g., as sub-blocks or as a subroutine) of block 806, where the system calibrates a first client device of a first user.

In block 1102, method 800 receives, at the server computer from the first client device, an electronic communication containing atmospheric pressure data, and location data.

In block 1104, method 800 determines a current altitude of the first client device, based on the atmospheric pressure data. The current altitude of the first client device is the height above sea level of the first client device. In particular, the altitude of the first client device may be determined from the atmospheric pressure data using the barometric formula.

In block 1106, method 800 determines, based on the location data, a current location of the user.

In block 1108, method 800 retrieves, from a ground level dataset (e.g., ground level table 312), a local ground level corresponding to the current location of the user.

In block 1110, method 800 determines, based on determining that the current altitude of the user is below the ground level at the current location of the user, that the user is underground. The location sharing system may use this information to determine that the user is in an underground transit system (e.g., Rapid transit, also known as heavy rail, metro, subway, tube, U-Bahn or underground).

As shown in FIG. 12 , user interface 1200 is an example of a user interface that may be displayed on a display screen of a second user. User interface 1200 includes a map 1202 depicting an avatar 1204 of the first user.

The avatar 1204 is a media content item associated with the first user and that may include a still image, animated image, video, or other content. The avatar may include a profile picture or a default icon. The location of the first user's avatar 1204 on the map GUI 1104 is representative of the current location of the first user. The system updates the location of the first user's avatar 1204 on the map 1202 as the location of the first user changes. The first user's avatar 1204 may be a selectable UI element triggering the display of a user interface (e.g., user interface 1300 of FIG. 13 ) including a map view centered on the selected avatar.

If the system determines a floor on which the first user is located (e.g., using method 800), the map 1202 displays an indication of the floor 1206 on which the first user is located. The floor 1206 on which the first user is located may be displayed as a text or an icon or a combination of both. An icon is a media content item that may include a still image, animated image, video, or other content.

In embodiments, elements of the map 1202, such as buildings, are displayed in three-dimensionally (3d). If the first user is in a building, the avatar of the first user is displayed in the 3D rendering of the building based on the 3D location of the user (latitude, longitude, and altitude). In embodiments, if the first user is in a building at night, the building is displayed with the lights turned on at the floor where the user is located. In embodiments, if the first user is located at the same floor as a third user (e.g., who is also a preferred contact of the second user), an indication that the first user and the third user are spending time together is displayed alongside the avatar of the first and third users. In embodiments, based on determining that a number of floors of a building exceeds a threshold (e.g., 2 floors), the building is identified as a high-rise building, as opposed to a low-rise building or house. An icon depicting the building is selected based on the building being a high-rise building or a low-rise building. In embodiments, if it is determined that the first user is in a plane, based on the altitude of the client device of the first user exceeding a threshold (e.g., 10,000 feet), an icon of a plane is displayed alongside the avatar of the first user. In embodiments, if it is determined that the altitude of the first user is increasing or decreasing, an indication that the user is moving up or down is displayed alongside the avatar of the first user.

As shown in FIG. 13 , user interface 1300 includes a map 1302 centered around the first user's avatar 1306. The user interface 1300 may include a current location 1310 of the first user (e.g. address). The user interface 1300 may also include an indication of the floor 1206 on which the first user is located. The user interface 1300 may also include a selectable user interface element 1308 for initiating or resuming a communication session with the first user via the messaging system 200.

Throughout this specification, plural instances may implement components, operations, or structures described as a single instance. Although individual operations of one or more methods are illustrated and described as separate operations, one or more of the individual operations may be performed concurrently, and nothing requires that the operations be performed in the order illustrated. Structures and functionality presented as separate components in example configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements fall within the scope of the subject matter herein.

Although an overview of the inventive subject matter has been described with reference to specific example embodiments, various modifications and changes may be made to these embodiments without departing from the broader scope of embodiments of the present disclosure.

The embodiments illustrated herein are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed. Other embodiments may be used and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. The Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled.

As used herein, the term “or” may be construed in either an inclusive or exclusive sense. Moreover, plural instances may be provided for resources, operations, or structures described herein as a single instance. Additionally, boundaries between various resources, operations, modules, engines, and data stores are somewhat arbitrary, and particular operations are illustrated in a context of specific illustrative configurations. Other allocations of functionality are envisioned and may fall within a scope of various embodiments of the present disclosure. In general, structures and functionality presented as separate resources in the example configurations may be implemented as a combined structure or resource. Similarly, structures and functionality presented as a single resource may be implemented as separate resources. These and other variations, modifications, additions, and improvements fall within a scope of embodiments of the present disclosure as represented by the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

“Signal Medium” refers to any intangible medium that is capable of storing, encoding, or carrying the instructions for execution by a machine and includes digital or analog communications signals or other intangible media to facilitate communication of software or data. The term “signal medium” shall be taken to include any form of a modulated data signal, carrier wave, and so forth. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a matter as to encode information in the signal. The terms “transmission medium” and “signal medium” mean the same thing and may be used interchangeably in this disclosure.

“Network” refers to one or more portions of a network that may be an ad hoc network, an intranet, an extranet, a virtual private network (VPN), a local area network (LAN), a wireless LAN (WLAN), a wide area network (WAN), a wireless WAN (WWAN), a metropolitan area network (MAN), the Internet, a portion of the Internet, a portion of the Public Switched Telephone Network (PSTN), a plain old telephone service (POTS) network, a cellular telephone network, a wireless network, a Wi-Fi® network, another type of network, or a combination of two or more such networks. For example, a network or a portion of a network may include a wireless or cellular network and the coupling may be a Code Division Multiple Access (CDMA) connection, a Global System for Mobile communications (GSM) connection, or other types of cellular or wireless coupling. In this example, the coupling may implement any of a variety of types of data transfer technology, such as Single Carrier Radio Transmission Technology (1×RTT), Evolution-Data Optimized (EVDO) technology, General Packet Radio Service (GPRS) technology, Enhanced Data rates for GSM Evolution (EDGE) technology, third Generation Partnership Project (3GPP) including 3G, fourth generation wireless (4G) networks, Universal Mobile Telecommunications System (UMTS), High Speed Packet Access (HSPA), Worldwide Interoperability for Microwave Access (WiMAX), Long Term Evolution (LTE) standard, others defined by various standard-setting organizations, other long-range protocols, or other data transfer technology.

“Processor” refers to any circuit or virtual circuit (a physical circuit emulated by logic executing on an actual processor) that manipulates data values according to control signals (e.g., “commands”, “op codes”, “machine code”, etc.) and which produces corresponding output signals that are applied to operate a machine. A processor may, for example, be a Central Processing Unit (CPU), a Reduced Instruction Set Computing (RISC) processor, a Complex Instruction Set Computing (CISC) processor, a Graphics Processing Unit (GPU), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Radio-Frequency Integrated Circuit (RFIC) or any combination thereof. A processor may further be a multi-core processor having two or more independent processors (sometimes referred to as “cores”) that may execute instructions contemporaneously.

“Machine-Storage Medium” refers to a single or multiple storage devices and/or media (e.g., a centralized or distributed database, and/or associated caches and servers) that store executable instructions, routines and/or data. The term shall accordingly be taken to include, but not be limited to, solid-state memories, and optical and magnetic media, including memory internal or external to processors. Specific examples of machine-storage media, computer-storage media and/or device-storage media include non-volatile memory, including by way of example semiconductor memory devices, e.g., erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), FPGA, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks The terms “machine-storage medium,” “device-storage medium.” “computer-storage medium” mean the same thing and may be used interchangeably in this disclosure. The terms “machine-storage media,” “computer-storage media,” and “device-storage media” specifically exclude carrier waves, modulated data signals, and other such media, at least some of which are covered under the term “signal medium.”

“Component” refers to a device, physical entity, or logic having boundaries defined by function or subroutine calls, branch points, APIs, or other technologies that provide for the partitioning or modularization of particular processing or control functions. Components may be combined via their interfaces with other components to carry out a machine process. A component may be a packaged functional hardware unit designed for use with other components and a part of a program that usually performs a particular function of related functions. Components may constitute either software components (e.g., code embodied on a machine-readable medium) or hardware components. A “hardware component” is a tangible unit capable of performing certain operations and may be configured or arranged in a certain physical manner. In various example embodiments, one or more computer systems (e.g., a standalone computer system, a client computer system, or a server computer system) or one or more hardware components of a computer system (e.g., a processor or a group of processors) may be configured by software (e.g., an application or application portion) as a hardware component that operates to perform certain operations as described herein. A hardware component may also be implemented mechanically, electronically, or any suitable combination thereof. For example, a hardware component may include dedicated circuitry or logic that is permanently configured to perform certain operations. A hardware component may be a special-purpose processor, such as a field-programmable gate array (FPGA) or an application specific integrated circuit (ASIC). A hardware component may also include programmable logic or circuitry that is temporarily configured by software to perform certain operations. For example, a hardware component may include software executed by a general-purpose processor or other programmable processor. Once configured by such software, hardware components become specific machines (or specific components of a machine) uniquely tailored to perform the configured functions and are no longer general-purpose processors. It will be appreciated that the decision to implement a hardware component mechanically, in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software), may be driven by cost and time considerations. Accordingly, the phrase “hardware component” (or “hardware-implemented component”) should be understood to encompass a tangible entity, be that an entity that is physically constructed, permanently configured (e.g., hardwired), or temporarily configured (e.g., programmed) to operate in a certain manner or to perform certain operations described herein. Considering embodiments in which hardware components are temporarily configured (e.g., programmed), each of the hardware components need not be configured or instantiated at any one instance in time. For example, where a hardware component comprises a general-purpose processor configured by software to become a special-purpose processor, the general-purpose processor may be configured as respectively different special-purpose processors (e.g., comprising different hardware components) at different times. Software accordingly configures a particular processor or processors, for example, to constitute a particular hardware component at one instance of time and to constitute a different hardware component at a different instance of time. Hardware components can provide information to, and receive information from, other hardware components. Accordingly, the described hardware components may be regarded as being communicatively coupled. Where multiple hardware components exist contemporaneously, communications may be achieved through signal transmission (e.g., over appropriate circuits and buses) between or among two or more of the hardware components. In embodiments in which multiple hardware components are configured or instantiated at different times, communications between such hardware components may be achieved, for example, through the storage and retrieval of information in memory structures to which the multiple hardware components have access. For example, one hardware component may perform an operation and store the output of that operation in a memory device to which it is communicatively coupled. A further hardware component may then, at a later time, access the memory device to retrieve and process the stored output. Hardware components may also initiate communications with input or output devices, and can operate on a resource (e.g., a collection of information). The various operations of example methods described herein may be performed, at least partially, by one or more processors that are temporarily configured (e.g., by software) or permanently configured to perform the relevant operations. Whether temporarily or permanently configured, such processors may constitute processor-implemented components that operate to perform one or more operations or functions described herein. As used herein. “processor-implemented component” refers to a hardware component implemented using one or more processors. Similarly, the methods described herein may be at least partially processor-implemented, with a particular processor or processors being an example of hardware. For example, at least some of the operations of a method may be performed by one or more processors 1004 or processor-implemented components. Moreover, the one or more processors may also operate to support performance of the relevant operations in a “cloud computing” environment or as a “software as a service” (SaaS). For example, at least some of the operations may be performed by a group of computers (as examples of machines including processors), with these operations being accessible via a network (e.g., the Internet) and via one or more appropriate interfaces (e.g., an API). The performance of certain of the operations may be distributed among the processors, not only residing within a single machine, but deployed across a number of machines. In some example embodiments, the processors or processor-implemented components may be located in a single geographic location (e.g., within a home environment, an office environment, or a server farm). In other example embodiments, the processors or processor-implemented components may be distributed across a number of geographic locations.

“Carrier Signal” refers to any intangible medium that is capable of storing, encoding, or carrying instructions for execution by the machine, and includes digital or analog communications signals or other intangible media to facilitate communication of such instructions. Instructions may be transmitted or received over a network using a transmission medium via a network interface device.

“Computer-Readable Medium” refers to both machine-storage media and transmission media. Thus, the terms include both storage devices/media and carrier waves/modulated data signals. The terms “machine-readable medium,” “computer-readable medium” and “device-readable medium” mean the same thing and may be used interchangeably in this disclosure.

“Client Device” refers to any machine that interfaces to a communications network to obtain resources from one or more server systems or other client devices. A client device may be, but is not limited to, a mobile phone, desktop computer, laptop, portable digital assistants (PDAs), smartphones, tablets, ultrabooks, netbooks, laptops, multi-processor systems, microprocessor-based or programmable consumer electronics, game consoles, set-top boxes, or any other communication device that a user may use to access a network.

“Ephemeral Message” refers to a message that is accessible for a time-limited duration. An ephemeral message may be a text, an image, a video and the like. The access time for the ephemeral message may be set by the message sender. Alternatively, the access time may be a default setting or a setting specified by the recipient. Regardless of the setting technique, the message is transitory. 

What is claimed is:
 1. A method comprising: accessing, at a server computer, historical data including historical location values and historical atmospheric pressure values collected from a plurality of client devices over a period of time; estimating, by the server computer, a barometer bias of a first client device by solving an equation system, the equation system having a plurality of parameters including the historical location values and the historical atmospheric pressure values for the plurality of client devices, the plurality of parameters further including an unknown parameter of a barometer bias for each client device of the plurality of client devices; providing for calibrating the first client device based on the barometer bias of the first client device; determining, by the server computer, a floor level on which a first user associated with the first client device is located, based on current location data and a current altitude of the first client device as calibrated; and causing, on a second client device associated with a second user, display of a user interface including a map, an avatar of the first user positioned within the map based on the current location data, and an indication of the floor level together with the avatar of the first user.
 2. The method of claim 1, further comprising, prior to determining the floor level: receiving, at the server computer, from the first client device, an electronic communication containing the current location data and current atmospheric pressure data; and determining, by the server computer, the current altitude of the first client device, based on the current location data and the current atmospheric pressure data.
 3. The method of claim 2, further comprising: determining, based on the current location data, a current location of the first user; retrieving, from a ground level dataset, a ground level at the current location of the first user; and determining, based on determining that the current altitude of the first user is below the ground level at the current location of the first user, that the first user is underground.
 4. The method of claim 3, further comprising: determining, based on determining that the first user is underground and based on determining that a speed of the first user is above a speed threshold, that the first user is in an underground transit system; and based on determining that the first user is in the underground transit system, initiating transmission of data to a second client device of a second user, the data comprising an indication that the first user is in the underground transit system, for display on a display screen of the second client device.
 5. The method of claim 1, wherein causing display of the user interface comprises initiating transmission of data to the second client device, the data comprising the floor level on which the first user is located, for display on a display screen of the second client device.
 6. The method of claim 5, wherein initiating transmission of data to the second client device includes attaching the data to an ephemeral message accessible for a predetermined duration of time, and wherein display on the display screen of the second client device includes: receiving a request from the second client device to access the ephemeral message; in response to the request, causing the ephemeral message to be displayed on the second client device; and ceasing display of, and access to, the ephemeral message in response to expiration of the predetermined duration of time.
 7. The method of claim 1, further comprising: receiving, at the server computer, from the first client device, the first client device being associated with a first user, an electronic communication containing current location data and current atmospheric pressure data; determining, by the server computer, based on the current location data, a current location of the first client device; determining, by the server computer, based on the current atmospheric pressure data, a current altitude of the first client device; determining, by the server computer, based on the current location data, that the first user is at ground level; and determining, by the server computer, based on the current altitude of the first client device, a ground level at the current location of the first user.
 8. The method of claim 7, further comprising: adding the ground level, in association with the current location of the first user, to a ground level dataset; and building a ground level map based on the ground level dataset.
 9. The method of claim 7, wherein determining that the first user is at ground level comprises: determining that a speed of the first user is above a speed threshold over a distance that is longer than a distance threshold.
 10. The method of claim 1, wherein the plurality of parameters further comprise historical altitude values, historical ground level values, and historical atmospheric pressure at sea level values for the plurality of client devices.
 11. The method of claim 1, wherein estimating the barometer bias of the first client device is based on a law of large numbers (LLN), by which accuracy in estimating the barometer bias of the first client device improves with increased amounts of the historical data.
 12. A system comprising: one or more processors; and a memory storing instructions that, when executed by the one or more processors, configure the system to perform operations comprising: accessing historical data including historical location values and historical atmospheric pressure values collected from a plurality of client devices over a period of time; estimating a barometer bias of a first client device by solving an equation system, the equation system having a plurality of parameters including the historical location values and the historical atmospheric pressure values for the plurality of client devices, the plurality of parameters further including an unknown parameter of a barometer bias for each client device of the plurality of client devices; providing for calibrating the first client device based on the barometer bias of the first client device, determining a floor level on which a first user associated with the first client device is located, based on current location data and a current altitude of the first client device as calibrated; and causing, on a second client device associated with a second user, display of a user interface including a map, an avatar of the first user positioned within the map based on the current location data, and an indication of the floor level together with the avatar of the first user.
 13. The system of claim 12, the operations further comprising, prior to determining the floor level: receiving, from the first client device, an electronic communication containing the current location data and current atmospheric pressure data; and determining the current altitude of the first client device, based on the current location data and the current atmospheric pressure data.
 14. The system of claim 12, wherein causing display of the user interface comprises initiating transmission of data to the second client device of a second user, the data comprising the floor level on which the first user is located, for display on a display screen of the second client device.
 15. The system of claim 14, wherein initiating transmission of data to the second client device includes attaching the data to an ephemeral message accessible for a predetermined duration of time, and wherein display on the display screen of the second client device includes: receiving a request from the second client device to access the ephemeral message; in response to the request, causing the ephemeral message to be displayed on the second client device; and ceasing display of, and access to, the ephemeral message in response to expiration of the predetermined duration of time.
 16. The system of claim 11, the operations further comprising: receiving, from the first client device, the first client device being associated with a first user, an electronic communication containing current location data and current atmospheric pressure data; determining, based on the current location data, that the first user is at ground level; determining, based on the current atmospheric pressure data, a current altitude of the first client device; determining, based on the current location data, a current location of the first client device; and determining, based on the current altitude of the first client device, a ground level at the current location of the first user.
 17. The system of claim 16, the operations further comprising: adding the ground level, in association with the current location of the first user, to a ground level dataset; and building a ground level map based on the ground level dataset.
 18. A non-transitory computer-readable storage medium, the computer-readable storage medium including instructions that when executed by a computer, cause the computer to perform operations comprising: accessing historical data including historical data including historical location values and historical atmospheric pressure values collected from a plurality of client devices over a period of time; estimating a barometer bias of a first client device by solving an equation system, the equation system having a plurality of parameters including the historical location values and the historical atmospheric pressure values for the plurality of client devices, the plurality of parameters further including an unknown parameter of a barometer bias for each client device of the plurality of client devices; providing for calibrating the first client device based on the barometer bias of the first client device; determining a floor level on which a first user associated with the first client device is located, based on current location data and a current altitude of the first client device as calibrated; and causing, on a second client device associated with a second user, display of a user interface including a map, an avatar of the first user positioned within the map based on the current location data, and an indication of the floor level together with the avatar of the first user. 